Hitherto, there is known a coil component (composite coil), such as an impedance element or an inductance element, in which a coil formed by winding a conductive wire is incorporated in a core portion containing metal magnetic substance powder and resin.
For example, Japanese Unexamined Patent Application Publication No. 2014-225590 discloses a manufacturing method for a surface-mounted inductor, the manufacturing method including the steps of winding a conductive wire to form a coil, forming a core portion incorporating the coil with use of an encapsulation material, which is made of mainly metal magnetic substance powder and resin, such that at least parts of both end portions of the coil are exposed at surfaces of the core portion, setting smoothness of a surface of at least part of a region of the core portion where an outer electrode is formed to be lower than smoothness of a surface around the former surface, and forming the outer electrode in the core portion to be electrically conducted to the coil.
The core portion containing the metal magnetic substance powder and the resin tends to have a smaller thermal conductivity. This is attributable to the fact that the thermal conductivity of the metal magnetic substance powder is comparatively small. When the thermal conductivity of the core portion is small, there is a tendency that heat is less apt to dissipate to the outside on the occurrence of heating of the coil (so-called copper loss) and/or the occurrence of heating of the metal magnetic substance powder contained in the core portion (so-called iron loss), and that temperature of the coil component increases. A temperature rise of the coil component is apt to cause malfunction of an IC, etc. disposed near the core portion, and/or heating of an electronic device that includes the coil component. For that reason, an improvement in heat dissipation characteristics of the core portion is demanded.
On the other hand, the coil component is demanded to have a higher inductance value (L value).